Power transmission



April 1941? R. 1 TWEEDALE 2.237.018

POWER TRANSMIS S ION Filed Feb. 11, 1937 6 Sheets-Sheet 1 INVENTOR April 1, 1941. R. TWEEDALE POWER TRANSMISSION Filed Feb. 11', 1957 6 Sheets-Sheet 2 INVENTOR April 1, 1941. R. TWEEDALE 3 18 POWER TRAN SMISSION I Filed Feb. 11, 1937 6 Sheets-Sheet 5' F 53 E g.

i 1 I Hi J J L i h 5 INVENTOR April 1, 1941. TWEEDALE 2.237.018

' POWER TRANSMISSION Filed Feb. 11, 1937 v 6 Sheets-Sheet 4 INVENTOR W i M Patented Apr. 1, 1941 POWER TRANSMISSION Ralph L. Tweedale, Waterbury, Coma, assignor to The Waterbury Tool Company, Waterbury, Conn., a corporation of Connecticut Application February 11, 1937, Serial No. 125.252

9 Claims.

This invention relates to' power transmissions and more particularly to those of the type comprising two or more fluid pressure'energy translating devices, one of which may function as a pump and another as a fluid motor. Devices of this character are usually constructed as a separate unit for connection to a prime mover and to a load device.

It is an object of the present invention to provide a power unit comprising an electric motor prime mover and a variable speed power transmission which is constructed as a single compact- Another object of the invention is to provide a" power transmission in which simple' and effective means are utilized for automatically maintaining the proper clearance at the rotary valving surfaces.

A further object is to provide a fluid pressure energy translating device in which the fluid pressure forces are balanced both radially and axially and wherein the effective displacement, may be varied by altering the phase relation of the valve action with respect to the piston action and to provide therein means for compensating certain disturbances of the valve action at small effective displacements.

Further objects and advantages of the present invention will be apparent from the following description,- reference being had to the accompanying drawings wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a longitudinal cross section of a motortransmission unit incorporating a preferred form of the present invention.

Fig. 2 is a cross section on line 2--2 of Fig. 1.

Fig. 3 is a cross section on line 33 of Fig. 1.

Fig. 4 is a cross section on line 44 of Fig. 1.

Fig; 5 is a cross section on line 5-5 of Fig. 1.

Fig. 6 is a cross section on line 66 of Fig. 7.

Fig. 7 is an end view showing the invention embodied in a variable displacement pump.

Referring now to Fig: l the novel motor-transmission unit comprises a-main frame section I0 which is of generally tubular shape with a transverse partition I2 extending across-the same, near the mid point. The partition I2 divides the casing member ID into a motor compartment I3 on the right, and a pump compartment I5 on the left. The partition I2 is dished as shown in Fig. 1 to provide space for the motor windings I4 on the right-hand side of the partition and to provide a space on the left-hand side of the partition and radially inward for race It and balls I8, later to be described. The partition I2 is further provided with a central bore within which are mounted bearings 20 and an oil seal 22. An end plate 24 is secured to the casing member II) by bolts 26 and has a central bore in which are mounted bearings 28. A shaft 30 is journalled in the bearings 20 and28 and carries an electric motor rotor 32 of any suitable construction. A stator 34 carries the windings I4 and is positioned between a shoulder 36 on the casing I0 and a pump 44 which is illustrated as of the internalexternal gear type. Suitable arcuate inlet and outlet ports 46 and 48 are provided adjacent the recess 40 (seeFig. 3). The inlet port 46 communicates by a passage 50 formed in the end plate 24 and a passage 52 formed in the frame member III with a sump 54 which is formed integrally with the. frame member ID at the bottom thereof as is apparent from Fig. 4. The sump 54 is separated from the motor compartment I3 but opens into the pump compartment I5 on the left-hand side of the partition I2. Theoutlet port 48 of the pump 44 communicates by a passage 56 with a groove 58 formed in the shaft 30. A transverse bore 60 and longitudinal bore 62 serve as delivery passages to a larger bore 64, formed in the lefthand end of the shaft 30. A suitable relief valve 66 serves to by-pass fluid from the port 48 to the port 46 when a predetermined pressure is exceeded in the port 4 Within the pump compartment I5 there is mounted on the shaft 30 a cylinder barrel 68 having a plurality of radial cylinders Ill formed therein. The barrel 68 is connected to the shaft 30 by pivoted keys I2 which permit a limited universal joint action between the shaft 30 and the barrel 68 to provide for slight inaccuracies in alignment. Communicating with each'cylinder III at the inner end thereof is a longitudinal bore I4 extending from side to side of the barrel 58 providing individual oppositely facing cylinder ports 18 and 18. Within each cylinder 18 is slidrolling fit between the ball and the sleeve. Slidably and rotatably mounted in the casing member I8 is a race member 88 having a generally oval race 88 on which the balls 84 may roll. The race 88 is preferably formed with across section corresponding to the curvature of the balls 84. The race member 88 is provided with teeth 98 on a portion of its outer periphery which cooperate with a. worm 92 to vary the angular position of the oval race 88. A shaft 84 and handwheel 88 permit manual operation of the worm 92.

Secured to the casing section I8 at the lefthand end thereof by bolts 98 is an end plate I88. The latter carries central bearings I82 on which a'shaft I84 is journalled, an oil seal I88 being provided to prevent the escape of oil along this shaft; The end plate I88 provides a fluid motor chamber I88 and serves also as a mounting for a valve plate H8 which is. slidably but non-rotatably secured to the interior of the end plate I88 by keys III. In the motor chamber I 88 is a second cylinder barrel II2 similar to the cylinder barrel 88' having cylinders H4 in which are slidably. mounted, piston sleeves II8 having spherical sockets 8 to receive balls I28. The barrel M2 is secured to the shaft I84by keys I22 similar to the:key s: 12. The shaft I84 is journalled ini the valve? plate I I8 and has its end reduced in diameter at I24 to be received in 'the enlarged bore 84 on the shaft 38. A central passage I28 and cross bore I28 connect a groove I38 on the shaft I84 with the delivery passage 82 of the pump 44. v

The end plate I88 also supports a race member Iz32 having an oval race I34 similar to the race 88 The race member I32 is mounted so as to be axially slidable but non-rotatable with respect to the end plate I88 by means of keys I33. Each of the cylinders II4 of the barrel H2 is provided with individual cylinder ports I38 and I38 similar to the ports 18 and 18.

The cylinder barrel H2 is provided withflat faces which abut a flat face I48 formed on the end plate I88 and a flat face I42 on the valve plate H8. The cylinder 88 is likewise formed with flat faces which abut against a flat face I44 on the valve plate III and a flat face I48 formed on a reaction member I48. The right-hand face of the reaction member I48 is provided with a plurality of cam races I58, (Fig. 4) each of which forms a small portion of a helix formed to lit the balls I 8. The halls I8 are disposed between the cam tracks I58 and a toroidal race I52 formed in the race member l8. plate lllis a spiral I54 which has it other end secured to an adjustable ring I58 mounted in the casing member II. The ring I58 is provided with teeth I58 which engage with a worm I 84 having a spring-pressed piston I88. Eachof the passages I88, I18, I12 and I14 is positioned equidistantly between the main valve ports I 82 but radially outward therefrom. Also within the valve. plate are mountedreplenishing valves I 88 which communicate with a passage I98 leading from the groove I38. The valves I88 open into two adjacent ports I82. The diametrically opposite ports Hi2 v are connected by transverse passages I92. One of the ports I82 communicates by a bore I94 with a relief valve I98 which is adapted to open communication with the adjacent port I82 through a passage I 98 whenever the pressure in either port I62 exceeds, a predetermined value. I

In operation assuming the active part, of the system, that is the cylinders 18 and H4 and the valve ports, to be filled with oil and with a suitable quantity of oil in the sump 54, rotation of the shaft 38 by the motor 32-34 drives'the barrel 88 causing the balls 84 to be carried around the oval track 88. The pistons 88 are thereby reciprocated alternately in and out at the rate of four strokes per revolution. With the race member '88 positioned as illustrated in Fig. 5, it will be seen that each piston stroke begins as a port 18 passes on to one of the valve ports I82 and ends as the port 18 passes off from the valve port I82. Two opposite ports I 82 thus supply fluid to the cylinders 18 on the outward stroke of the piston while the pistons deliver fluid to the other two ports I82 on their inward strokes. The cylinder barrel II2 receives this fluid delivered from the pump through two of the ports I62 and the pressure is exerted on pistons H8 and balls I 20, causing the barrel II2 to turn at. the same speed as the barrel 18. On the inward strokes of the pistons I I8, oil is returned to the pump through the other two ports I82. For example if the barrel is rotated clockwise in Fig. 5, pistons 88 will move in during their travel through the upper right and lower left quadrants and fluid will be delivered to the ports I82 located in these quadrants. Likewise the pistons 88 will move out during their travel through the upper left and lower right quadrants and oil will be withdrawn from the ports I82located in those quadrants.

- Thus under these conditions the ports I82 at the Secured to the reaction I88 by which the angular position of the ring I58 may be adjusted.

Referring now to Fig. 2 the construction of the valve plate III isthere illustrated. It will be seen that there are provided four arcuate passage I82 extending transversely through the plat: from the'surface I42 to the surface I44 and cooperating with the cylinder ports 18 and I38. The cylinder barrel 88 is provided with port extensions I84 adjacent the ports 18, and with similar port extensions I88 adjacent the ports 18. The port extensions I84 are adapted to cooperate with passages I88 I18, I12 and I14 which lead upper right and lower left quadrants become the pressure ports while the other ports I82 become the suction ports.

The reaction plate I48 is urged-thy the spring I54 to turn in a direction opposite to that in which the shaft 38 turns. This action causes the plate I48 to roll on the balls I8 toward the shallow ends of the track I58. The plate I48 is thus urged by a screw action to the left in Fig. 1 until the flat surfaces of the cylinder barrels, the valve plate and the casing I 88 are urged into sealing relationship. This action continues until the frictional drag of the barrel 88 on the-plate I 48 is equal to the force exerted by the spring I54 when a balance is reached such that the plate I48 is maintained stationary. As conditions change requiring a different position of the plate I48, the

plate adjusts itself automatically to the point where the frictional drag exactly balances the force of the'spring I54. 1 Thus, changes in oil viscosity and wear on' the flat-surfaces of'the'various members are compensated for automatically and independently of the fluid pressure at which the and I02 are balanced by the fact that for each piston there is another piston diametrically opposite which is moving oppositely.

The speed and direction of the shaft I04 may be varied by changing the position of the race member 86. Thus by operation of the handwheet. 96 if the race he turned counterclockwise in Fig. 5 through an angle less than 45, the phase relation between the piston strokes and the valveaction at the ports I62 is altered so that during a portion of the inward stroke of each piston fluid is delivered to the ports I62 which are on the suction side and likewise during a por-. tion of the outward stroke of each piston, fluid is withdrawn from the ports I62 which are on the delivery side. The farther the race 86 is turned away from the full discharge position of Fig. 5, the longer is each piston connected to the wrong port during a part of each stroke, until, when the 45 position is reached, the transfer from one port I62 to the next occurs exactly at mid stroke of each piston. 'At this position the net displacement is zero. Upon further rotation counterclockwise the net displacement increases but the direction of flow through the ports I62 is reversed, thus reversing the shaft I04. After 90 movement of the race 86 from the position of Fig. 5, the pump displaces the maximum quantity of fluid in the reverse direction.

It will be seen that at any setting of the handwheel 96 other than the two full displacement positions, each piston is moving either inwardly v or outwardly as its corresponding port 16, passes 40 across the blank face I44 between adjacent ports I62. In order'to relieve the fluid which is dis-/ placed during this instant onthe inward stroke and to supply fluid on the outward stroke, the passages I66, I10, I12 and I14 and the port extensions I64 are provided. Thus as each port 16 is about to leave'one of the ports I62. the port extension I64 fopens to the passage I66, for example. -If the piston happens to be on its inward stroke at this instant, fluid is discharged into the cylinder I18 and accumulates there by displacement of the piston I80.

Shortly after this port extension I64 leaves the passage I68, another port extension I64 connects to the passage I10 90 away. The corresponding piston is on its outward stroke so that the fluid'stored in the cylinder I16 is delivered through the passage I16 to supply the void which would otherwise be created while the port 16 crosses from one port I62 to the next. A similar action takes place at the passages I12 and I14. In this; manner the fluid impact and cavitation effects which have heretofore prevented the sue- Y cessful use of displacement variation by changing plenishing valves I88. In this way the active part of the system is constantly replenished with oil from the sump without requiring that the entire case be filled with oil. I

I It will be seen that end cap- I00 carries not only the entire fluid motor but the valve plate also. If it is' desired to assemble a transmission unit for use where the maximum output is greater than or less than the motor speed, the same parts including the valve plate H0 and all parts to the right thereof in Fig. 1 may be assembled to a different end plate I00 containing a fluid motor of a difierent displacement than the pump 60. Likewise, by the substitution of a fixed valve plate 200 in place of the end plate IIO having pipe connections 202 connecting to the ports I62 as illustrated in Figs. 6 and 7, a variable dlsplacement motor driven pump may be provided using the same parts which go to make up the unit il lustrated'in Fig. l. The -valve plate 200 may be provided with a flxed stud 204 which cooperates with the bore 64 in a manner analogous to the portion I24 of shaft I04.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be. understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. In a fluid pressure energy translating device the combination of two relatively rotatable members, means forming an expansible chamber in one member, motion converting means for expanding and contracting said chambers in response to relative rotation of saidmembers, means forming an inlet and an outlet passage in the other member, said members each maving a flat face in abutting relation with .each other and containing ports communicating respectively with the expansible chamber and to the inlet and outlet passages, a pressure plate having aflat face, a

one member, motion converting means for ex-' pending and contracting said chambers in response to relative rotation of said members, means forming an inlet and an outlet passage in the other member, said members each having a flat face in abutting relation with each other and containing ports communicating respectively with the expansible chamber and to the inlet and outlet passages, a pressure plate having a flat face, a flat face on the one member abutting the flat face of the pressure plate and having a pressure balancing port communicating with the expansible chamber and of equal area and directly opposed to the other port in the one member, helical means for causing the pressure plate to move axially toward the one member upon rotation of the plate in one direction, and resilient means for urging the plate in that direction.

3. In a hydraulic variablespeed transmission the combination of two fluid pressure energy translating devices, each comprising a member having an expansible chamber therein and means for variably expandingand contracting said chamber, a single member disposed between said members having an inlet and an outlet passageconnecting said translating devices, means mounting the members for relative rotation of the two expansible chamber members and the other member and permitting slight axial movement of, all of the members toward and away from one another, said members having flat faces in abutting relation and containing ports leading respectively to the expansible chamber and to the inlet and outlet passages, and means for urging said flat faces into contact to maintain a substantially constant frictional drag between the faces. 7

4. In a hydraulic variable speed transmission the combination of two fluid pressure energy translating devices, each comprising a member having an expansible chamber therein and means for variably expanding and contracting said chamber, a single member disposed between said members having an inlet and an outlet passage connecting said translating devices, means mounting the members for relative rotation of the two expansible chamber members and the other member and permitting slight axial movement of all of the members toward and away from one another, said members having flat faces in abutting relation and containing ports leading respectively to the expansible chamber and to the inlet and outlet passages, and a single means for urging all of said flat faces into fluid sealing engagement. a

5. In a fluid pressure energy translating de vice the combination of a cylinder member having a plurality of open-ended radial bores, pistons reciprocable in said bores, a race member having a substantially oval race thereon for reciprocating said pistons, means mounting said members for rotation of one relative to the other,

a valve member associated with the race member and having two pairs of inlet and outlet ports, a port in the cylinder member connecting to each bore and cooperating with said inlet and outlet. ports, means for-varying-the phase relation between the race member and the valve member for varying the net displacement of the device, and means providing for the supply and dis- Gil plurality of open-ended radial bores, pistonsre- -ciprocable in said bores, a race 'member having a substantially oval race thereon for reciprocating said pistons, means mounting said members for rotation of .one relative to the other, a valve member associatedwith the race member and having two pairs of inlet and outlet ports, a port in the cylinder member connecting to each bore and cooperating with said inlet and outlet ports, means for varying the phase relation between the race member and the valve member for varying the net displacement of the device, and means including an accumulator providing for the supply and discharge of fluid to and from said bores during the interval of transfer from an inlet to an outlet port and vice versa.

7. Ina variable speed power unit the combination of an electric motor, a .pump, a fluid motor,

said pump and electric motor being supported in a common casing member, a valve member PTO",

vided with a set of inlet and outlet ports for the pump and with a set of-inlet and outlet ports for the fluid motor and with passages connecting said sets of ports, and a second casing member for supporting the fluid motor and the valve member, said second casing member, fluid motor and valve member being removable as a unitand replaceable by a difierent casing member including a valve member for the pump and .piping connections to provide a motor-pump unit.

8. In a variable speed power unit the combination of an electricmotor, a pump, a fluid motor, said pump and electric motor being supported in a common casing member, said electric motor including an annular winding near the outer periphery thereof, a valve member provided charge of fluid to and from said bores during the-w the combination of a cylinder member having'a with a set of inlet and outlet ports for the pump and with a set of inlet and outlet .ports for the fluid motor and with passages connecting said sets of ports, and a second casing member for supporting the fluid motor and the valve member, said pump having a portion extending axially toward the motor and radially within said an nular winding.

9. In a variable speed power unit the combi-' nation of an electric motor, a pump; a fluid motor, said pump, fluid motor, and electric motor being supported in a common casing member,

said electric motor including an annular winding near the outer periphery thereof, said pump having a portion extending axially toward the 'motor and radially within said annular winding.

RALPH L. TWEEDALE. 

